C/2021 F1 (Lemmon-PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	12 Feb 2022	10.9	1.336 AU	1.416 AU	20h29m	+48°54'	64.7°	41.9°	340°
Perihelion	6 Apr 2022	9.6	1.000 AU	1.904 AU	01h06m	+24°18'	17.8°	17.8°	5°
Today	15 Dec 2025	30.1	12.436 AU	12.899 AU	13h22m	-73°15'	59.9°	3.9°	250°

The interactive orbit chart above shows the comet's path through the solar system and its position at the given date. Green and blue lines are shown perpendicular to the ecliptic plane: Green if the path is above the ecliptic plane, blue if it is below. (Left-click and drag to rotate the view; Right-click and drag to move the view; Use scroll wheel to zoom in our out.)

Light curve

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations from COBS. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 8.3 + 5 log[∆] + 14.9 log[r]). An additional green curve is displayed when an increase in apparent brightness is expected due to forward scattering of sunlight, which occurs when a dust-rich comet is located between the Earth and the Sun. (See Marcus 2007)

Charts

The all-sky chart below shows the path of the comet over the same period as the light curve. The comet's current position is marked yellow.

The following chart shows the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Orbital elements

The orbital elements of C/2021 F1 (Lemmon-PANSTARRS) are:

    e (Eccentricity)                : 0.9959980
    q (Perihelion distance)         : 0.9995700
    i (Inclination)                 : 107.27710
    Ω (Longitude of ascending node) : 203.58210
    ω (Argument of perihelion)      : 146.96330
    L (Longitude of perihelion)     : 214.51362
    B (Latitude of perihelion)      : 31.37100
    T (Time of perihelion passage)  : 2459676.25180
    P (Orbital period in years)     : 3947.34

    Epoch                           : 2025 Nov 12
    Reference                       : MPEC 2022-QD9

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-14 00:00 UT   13 21 52.9   -73 09 57    12.895   12.425   59.5    3.9   248   30.1 
2025-12-15 00:00 UT   13 22 21.2   -73 13 30    12.898   12.431   59.8    3.9   249   30.1 
2025-12-15 15:26 UT   13 22 39.0   -73 15 47    12.899   12.436   59.9    3.9   250   30.1 
2025-12-16 00:00 UT   13 22 48.7   -73 17 04    12.900   12.438   60.0    3.9   250   30.1 
2025-12-17 00:00 UT   13 23 15.6   -73 20 39    12.903   12.445   60.2    3.9   251   30.1 
2025-12-18 00:00 UT   13 23 41.6   -73 24 16    12.906   12.451   60.5    3.9   252   30.1 
2025-12-19 00:00 UT   13 24 06.9   -73 27 53    12.908   12.458   60.8    4.0   253   30.1 
2025-12-20 00:00 UT   13 24 31.4   -73 31 31    12.910   12.464   61.0    4.0   254   30.1 
2025-12-21 00:00 UT   13 24 55.1   -73 35 11    12.912   12.471   61.3    4.0   255   30.1 
2025-12-22 00:00 UT   13 25 18.0   -73 38 51    12.914   12.477   61.6    4.0   256   30.1 
2025-12-23 00:00 UT   13 25 40.0   -73 42 32    12.916   12.484   61.9    4.0   257   30.1 
2025-12-24 00:00 UT   13 26 01.2   -73 46 14    12.918   12.490   62.2    4.0   258   30.1 
2025-12-25 00:00 UT   13 26 21.5   -73 49 56    12.920   12.497   62.5    4.0   259   30.1 

    Terminology:
            
    delta:  distance between comet and earth in AU
    radius: distance between comet and sun in AU
    magn:   magnitude (brightness) estimate    
    ra:     right ascension in hours (24h = 360deg)
    dec:    declination in degrees
    elong:  elongation in degrees (angle sun-earth-comet)    
    phase:  phase angle in degrees (angle sun-comet-earth)        
    AU:     Astronomical Unit (mean distance between earth and sun: 149597870.7 km      
    

Orbital elements usually provided by the MPC (Minor Planet Center).
Observations contributed by observers worldwide, via COBS (Comet Observation Database) or the MPC (Minor Planet Center)
Calculations by a modified version of AAPlus, a C# implementation of the AA+ project by PJ Naughter from the algorithms presented in the book "Astronomical Algorithms" by Jean Meeus.
NGC2000 dso catalog and star labels from VizieR as provided by the Strasbourg astronomical Data Center.
Tycho2 catalog from the ESO archive.